Renal tubular acidosis (RTA) can lead to complications including growth failure, bone disease, and nephrocalcinosis. In the pediatric renal transplant population, these complications are associated with major medical and psychosocial consequences. The occurence of RTA after transplant has been observed for 30 years, but the causitive mechanisms are not well understood. The ultimate goal of this study is to elucidate the mechanisms causing post-transplant RTA, to correlate them with clinical course, and ultimately to identify risk factors.